Adjustable lighting fixture for hung ceiling installation

ABSTRACT

The present invention is directed to an improved lighting fixture especially adapted for use in a hung ceiling installation of the so-called &#39;&#39;&#39;&#39;grid&#39;&#39;&#39;&#39; type, and is characterized by the provision of a rectangular housing supported by the ceiling hanger structure and a separate rectangular diffuser frame dimensioned to telescope with the housing. The frame and housing includes complemental mounting devices permitting the vertical spacing between the diffuser and housing to be varied between preselected adjusted positions to compensate for the height characteristics of the ceiling tiles.

United States Patent [191 Woloski ADJUSTABLE LIGHTING FIXTURE FOR HUNGCEILING INSTALLATION [75] Inventor: Leonard E. Woloski, Jersey City,

[73] Assignee: Lightolier Incorporated, Jersey City,

[22] Filed: Mar. 29, 1973 [21] Appl. No.: 345,863

[52] US. Cl 240/5l.ll, 240/9 R, 240/144, 240/147 [51] Int. Cl. H05b33/02 [58] Field of Search 240/5l.11, 9, 144, 146, 240/147, 151

[5 6] References Cited UNITED STATES PATENTS I 2,376,715 5/1945 Naysmith240/51.1l R 3,344,270 9/1967 Ryder 3,609,338 9/1971 Kripp 240/146 X [451May 7,1974

FOREIGN PATENTS OR APPLICATIONS 393,532 11/1965 Switzerland 240/147Primary Examiner--Richard M. Sheen Attorney, Agent, or Firm-Arthur B.Colvin [5 7 ABSTRACT The present invention is directed to an improvedlighting fixture especially adapted for use in a hung ceilinginstallation of the so-called grid type, and is characterized by theprovision of a rectangular housing supported by the ceiling hangerstructure and a separate rectangular diffuser frame dimensioned totelescope with the housing. The frame and housing includes complementalmounting devices permitting the verti- .,cal spacing-between thediffuser and housing to be' varied between preselected adjustedpositions to compensate for the height characteristics of the ceilingtiles. 1 I

8 Claims, 1 rawin Flar iATENTED HAY 7 i974 SHEET 1 BF 4 SHEET 2 0F 4PATENTEBUAY 7 I974- PATENTEUIAY 71914 3310.085

' I SHEET 3 0F 4 ADJUSTABLE LIGHTING FIXTURE FOR HUNG CEILINGINSTALLATION BACKGROUND OF THE INVENTION 1. Field of the Invention Thepresent invention is in the field of lighting fixtures, and moreparticularly is in the field of lighting fixtures employed in hungceiling structures for use in so-called grid type ceilings.

2. The Prior Art In modern constructions, it is customary to provide aceiling incorporating ceiling tiles and lighting fixtures supportedbetween spaced, parallel, horizontally disposed grids fixed to the beamsof the building by intermediate hangers. Ceiling tiles are mounted tothe grid structure by connections effected along their longitudinalmarginal edges.

In a typical construction, the tile and fixture supports are comprisedof parallel, elongated steel or aluminum runners in the form of invertedTs, the vertical branch of the T, through the use of intermediatesupports, being hung from the building structure, the legs of the Textending horizontally to each side of the branch.

Rectangular ceiling tiles are typically seated with their lower sideedges resting upon the upper surfaces of the opposed legs of parallelrows of the T extrusions. Obviously, in such construction the downwardlyfacing surface of the T forms a visible component of the ceiling, andthe ceiling tiles are supported at a level above the legs of the Ts.

In a more recent development, the ceiling tiles are provided at theirside edges with longitudinally extending slots, the legs of the Textrusions supporting the tiles by extending into the slots. In suchinstances it will be evident that the lower surface of the tile isdisposed below the level of the legs of the T and that all, orsubstantially all, of the under face of the leg of the T will beobscured by the tile components below the level of the slot. Typically,lighting fixtures are mounted at spaced positions along the T supports,with the under face of the fixture seated atop the leg portions ofopposed rows of the T structure.

It is thus apparent that in existing lighting structures used inconnection with ceilings of the type described, the height of thefixture is established whereas the height of the tile may vary inaccordance with the type of tile used, e.g. the slotted or recessedtiles extending below the lower level of the T, and the unslotted andunrecessed tiles extending above the T level, It is, however, considereddesirable for the exposed portion of the lighting fixture to be disposedin co-planar alignment with the under face of the tile 'since, if thelight diffuser is above the tile, the side edges ofthe tiles adjacentthe fixture, which are often rough and unfinished, are highlyilluminated.

. SUMMARY OF THE INVENTION The present invention may be summarized asdirected to improvements in lighting fixtures of the type employed ingrid type hung ceilings, a principal advantage of the fixture of thepresent invention being the ability to adjust or vary the height atwhich the diffuser frame is disposed in accordance with the type ofceiling tile employed, whereby a desired relation between the lower edgeof the diffuser frame and ceiling tile may be maintained, without thenecessity of stocking different fixtures to be used with tiles ofdifferent types.

In accordance with the invention, a separable diffuser frame is providedwhich may be secured to the housing containing the light source in atleast two different heightwisely adjusted positions in accordance withtype of-tile employed.

In a preferred embodiment of the invention, the adjustability isprovided by incorporating in the housing a pair of side rails secured tothe housing to provide for relative adjustment in a vertical plane. Thediffuser assembly is pivotally secured to the rails such that thediffuser will be higher or lower in relation to the ceiling inaccordance with the adjusted position of the rails.

In accordance with modifications of the invention, the housing is itselfprovided with vertically displaced slots or tracks, the heightwiseorientation of the diffuser and housing being modified in accordancewith which of the slots is engaged with mounting means formed on thediffuser.

It is accordingly an object of the invention to provide an improvedlighting fixture for a hung ceiling installation.

A further object of the invention is the provision of a lighting fixtureof the type described wherein the heightwise orientation of the diffuserframe and the housing may be varied to provide a selected, desiredvertical adjustment between the diffuser and the ceiling tiles employed.

A further objectof the invention is the provision of a fixture of thetype described wherein the diffuser frame is mounted to a pair of siderails adapted to be fixed to the housing in at least two verticallyadjusted positions.

A still further object of the invention is to provide a modifiedlighting fixture wherein the diffuser is adapted to be connecteddirectly to the housing, the housing and diffuser being provided withvertically displaced complemental fastener means, the heightwiserelation of the diffuser and housing being varied in accordance with themanner in which the diffuser is connected to the housing.

To attain these objects and such further objects as may appear herein orbe hereinafter pointed out, reference is made to the accompanyingdrawings, forming a part hereof, in which:

FIG. I is a perspective view of a small portion of a tile type hungceiling installation employing a lighting fixture in accordance with theinvention;

FIG. 2 is an enlarged perspective view similar to FIG. 1', with thediffuser assembly shown in open position, providing access to the lightbulbs;

FIG. 3 is a fragmentary perspective view showing details ofconstruction;

FIG. 3a is a perspective view of the lighting fixture;

FIG. 4 is a vertical section taken on the line 4-4 of FIG. 3;

FIG. 5 is a vertical longitudinal section taken on the line 5-5 of FIG.3;

FIG. 6 is a fragmentary horizontal section taken on the line 66 of FIG.5;

FIGS. 7 and 8 are simplified fragmentary vertical cross sectional viewsthrough the structural support, housing, diffuser plate assemblies andceiling tile, showing modification of the heightwise orientations of thefixture parts to accommodate the same for tiles having differentcharacteristics;

FIG. 9 is a vertical section through a fixture in accordance with afurther embodiment of the invention;

FIG. 10 is a horizontal section taken on the line 10 10 of FIG. 9;

FIG. 11 is a vertical sectional view of still a further embodiment ofthe invention;

FIG. 12 is a vertical section taken on the line 12-12 of FIG. 11;

FIG. 13 is a vertical section through still a further embodiment of theinvention; and

FIG. 14 is a vertical section taken on the line 14l4 of FIG. 13.

Referring now to the drawings, there is shown in FIGS. 1 and 2 a ceilingC of the so-called hung or suspended type which is comprised of amultiplicity of rectangular ceiling tiles 10. As is conventional, alighting fixture L is mounted within a space provided by the omission ofa tile or tiles, it being understood that the number of such fixtures inany given subdivision of space will vary in accordance with the lightingrequirements of such space.

As best seen in FIG. 3, the tiles and fixtures are supported by a gridformed of a plurality of parallel rows of support members 11,essentially conventional in nature. The support members 11 may includean enlarged bead 12 received within a complemental socket extendingdownwardly from the hanger clip structure (not shown) depending from thebeams or other supports of the building.

Support members 11 are general T-shaped in vertical section, includingdepending vertical branch 13'and laterally extending legs 14, 15. Whileonly one such support assembly 11 has been shown, it will be understoodthat the ceiling grid is defined of a plurality of parallel rows ofsupports 11, the spacing of the supports being adjusted to coordinatewith the width of the ceiling tiles, such that tiles will rest betweenthe opposed or facing legs of adjacent supports.

In accordance with the invention, the lighting fixture includes ahousing 16 having a top wall 17, parallel side walls 20, 21 and parallelend walls 18, 19. A conventional light source 22 of any sort is mountedwithin the housing.

The walls 18, 19, 20, 21 define a generally rectangular structure whichis open at the bottom. The walls may include an inturned flange 23 whichsupports the weight of the housing, the flange being seated atop thebranch components of the support structures 11.

Referring to FIGS. 2, 3 and 4, the walls 18 and 19 are provided withrails 24, the rails being connected to the walls by an adjustmentmechanism which permits the rails to be adjusted in a vertical directionbetween at least two adjusted positions relative to the walls 18, 19.Since rails 24 and the manner of their connection to the walls l8, 19are identical, a description of one such rail and its connection to onewall 18 will suffice.

The rail 24, which is of a length slightly smaller than the length ofthe wall 18, is formed of bent metal and includes an upper ledge 25,side web 26, a horizontal support ledge 27, and a downwardly dependinglip 28 formed at the terminus of the ledge 27. The rail 24, adjacent itslateral extremities, is provided with a pair of support tabs 29 struckfrom the metal of the web 26, the tabs extending laterally outwardlybeyond the plane of the web.

The end wall 18, adjacent each of its lateral extremities, is formedwith a pair of vertically displaced slots 30, 31, within which the tabs29 may be selectively seated. The web portion 26 of the rail 24 isyieldingly maintained in abutting relation with the end wall 18 by aspring fixture 32 interposed between the rail and the wall.

The spring fixture includes an elongated cylindrical shank member 33,headed at its outer end 34. The wall 18 is provided with a vertical slot35, through which the shank 33 is passed, with the head 34 bearingagainst the outer face of the wall surrounding the slot 35. A butterflyspring 36 is fixed to the shank 33 at a central portion 37, the lateralarms 38, 39 of the spring bearing against the inner surface of the rail24 in spaced relation to the shank 33.

From the foregoing it will be apparent that the rail may be shifted tothe left, as viewed in FIG. 4, relative to the wall 18, which movementwill unseat or remove the tabs 29 from the slots, permitting the rail 24to be shifted vertically upwardly or downwardly.

When the tabs are in registry with the desired one of the slots 30 or31, the rail may be released, the spring 36 thereupon pressing the tabsthrough the desired slots, whereby adjustment in a vertical direction ofthe rail relative to the wall 18 may be effected.

While only two adjustment slots have been shown in FIGS. 3 to 5, it willbe apparent that more such slots may be provided. In practice, however,with existing tile constructions adjustability between two positions,displaced vertically about if! inch has been found sufficient.

A shield or diffuser plate assembly 40 in the form of a rectangularframe 41 carrying a light shielding or diffuser plate 42 is pivotallysecured between the spaced rails 24. Optionally but preferably, theframe 41 incorporates a substantial vertical dimension embodyingvertically extending side web 43 and an inwardly beveled flange 44terminating in an outwardly extending diffuser support ledge 45. Theframe 41 is attached between the rails 24 in such manner as to permit itto be pivoted clear of the normal horizontal position to the openposition shown in FIG. 2, to permit changing of bulbs. For this purpose,an opposed pair of pivot pins 46 extend laterally outwardly from theframe 41, the pins being seated on the ledge portion 27 of the rails 24.

The frame 41 is additionally provided with one or more latches 47 whichmay be engaged with the rails 24, it being understood that when thelatches are engaged, the plate 42 is disposed in the normal horizontalposition, release of the latches from the rails 24 enabling pivotalmovement to the position shown in FIG.

In FIG. 7 there is shown a tile 10' which is recessed at its lower edgesuch that the bottom face B of the tile is at a level substantiallybelow the legs l4, 15 of the support. The difi'user frame 41 in FIG. 7has been illustrated in the lowered position, whereby the apex 48 of thediffuser plate is in substantial co-planar alignment with the bottom Bof the tile.

In FIG. 8 there is illustrated a more conventional ceiling tile 10, theframe 41 being illustrated in its raised position within the housingwhereby the apex 48 is again in essentially co-planar alignment with thebottom B of the tile.

In the embodiment of FIGS. 9 and 10 wherein like parts have been givenlike numerals to the illustrations of the prior described embodiment,there is disclosed a variation in which the diffuser frame assembly 41is mounted directly to the housing 50 rather than through theinterpositioning of vertically shiftable rails, such as the rails 24.

As will be apparent from an inspection of FIG. 9, the housing 50 issupported on the inturned legs 14 and 15 of adjacent support members 11.Each of the two opposed parallel walls 51 (only one wall being shown,the parallel wall being identical) is provided with a pair ofhorizontally disposed, longitudinally extending slots 52, 53. It will beobserved that the slot 52 is located in a vertical plane above the planeof the slot 53.

The diffuser frame 41 is provided on its end wall portion 41' with amounting pin 54, it being appreciated that a similar, coaxially disposedmounting pin is secured to the wall of the diffuser assembly 41 which isparallel to the wall 41'.

The diffuser frame 41 includes a projecting latch extension member 55.The wall 56 of the housing is provided with a latch aperture 57. Insimilar fashion, the wall 58 of the housing 50 is provided with alatching aperture 59. It will be observed that the latching aperture 59and slot 53 are in co-planar alignment at a level below latchingaperture 57 and slot 52, which are likewise in co-planar alignment.

In the embodiment of FIGS. 9 and 10, if it is desired to support thediffuser frame in an upward or raised vertical position as respects thehousing 50, the pins 54 are mounted in the upper opposed slots 52 andlatches 55 in the upper latching apertures 57, whereupon the apex 48 ofthe frame 41 will be disposed'in substantial co-planar alignment withthe lowermost portion of the housing.

If it is desired that the diffuser frame 41 project below the level ofthe housing, the diffuser plate is removed from the housing, rotatedthrough 180 about a vertical axis, and the pins 54 seated within thelower slot 53, the latches 55 being passed into the lower latch receiverslots 59 in the wall 58.

It will be appreciated that after the pins have been seated within theappropriate slots, the frame may be pivoted to a horizontal position,and when the latches 55 are in registry with the latch receiverapertures 57, for instance, the entire diffuser plate may be bondilyshifted in a horizontal plate to engage the latches and receivers andlock the diffuser plate in its horizontal position. Obviously, differentlatching mechanism than the slot and latch tab 57 and 55, respectively,may be employed without departing from the spirit of the disclosure.

FIGS. 11 and 12 disclose a quite similar embodiment to that of FIGS. 9and 10. In this embodiment, the pins 54 of the diffuser frame ride ontracks 52, 53' corresponding to the slots 52, 53 of FIGS. 9 and 10.Preferably, the tracks 52, 53 are comprised of metal struck from andfolded inwardly relative to the walls 18 of the housing.

In the embodiment of FIGS. 11 and 12, the diffuser frame includeslaterally extending latch tabs 55 adapted to maintain the diffuser framein horizontal position by the tabs being seated selectively on one orthe other of the support ledges 57,- which are similarly struck from themetal of the wall 18.

The tracks 52', 53' are preferably provided with stop detents 60 whichprevent the pins 54 from inadvertently being shifted beyond the supports52' or 53' and falling clear of the lighting assembly.

The embodiment of FIGS. 13 and 14 is essentially similar in concept tothat of FIGS. 11 and 12, the upper support track 52" in FIGS. 13 and 14being an inwardly extending metal fold rather than a ledge struckinwardly from the body in the wall 18 of the housing.

In the embodiment of FIG. 13, the support detent 55" maintains thediffuser frame in horizontal position by being seated directly upon thetrack 52" in the upper position of the diffuser, or the bottom flange 53in the lower position of the diffuser.

From the foregoing it will be seen that the present invention isdirected to an improved lighting fixture incorporating as its basiccomponents a housing mounted in fixed position on the supporting gridwork of a hung ceiling installation, and a diffuser frame carrying adiffuser plate, the frame being susceptible of being mounted in at leasttwo different, vertically offset positions relative to the housing,whereby the heightwise relationship of the diffuser frame and housingmay be adjusted in accordance with the type of tile employed in theconstruction of the ceiling.

Through the use of a fixture of the type described, the installer isenabled readily to adapt the fixture to ceiling tiles of the variousstyles employed, rather than stocking different fixtures.

It will be apparent that variations in detail may occur to skilledworkers in the light of the instant disclosure, without departing fromthe spirit of the invention and, accordingly, the same is to be broadlyconstrued within the scope of the appended Claims.

Having thus described the invention and illustrated its use, what isclaimed as new and is desired to be secured by Letters Patent is:

l. A lighting fixture for a hung ceiling installation comprising, incombination, a housing member rectangular in horizontal section andincluding a top wall, a pair of spaced parallel side walls, and a pairof spaced parallel end walls, the lower marginal edges of said wallsdefining a downwardly open, horizontal mouth portion, a light source insaid housing, a pair of parallel rail members in said housing,respectively adjacent the end walls of said housing, adjustment meansoperatively connecting each of said rail members to said housing forsupporting said rails at a selected, predetermined, vertically adjustedposition relative to its adjacent end wall, a diffuser assemblyincluding a rectangular frame having an opening, a diffuser platemounted in said opening, hinge means adjacent one end of said framepivotally connecting said end of said frame to a corresponding pair ofsaid rail members, and releasable connector means mounted adjacent theend of said frame opposite said one end for releasably securing saidopposite end of said frame to said rail members.

2. The lighting fixture of claim 1 wherein said frame portion of saiddiffuser assembly includes a rectangular depending lip extending, in thesecured position of said frame, downwardly through said open mouthportion of said housing.

3. A lighting fixture in accordance with claim 2 wherein said adjustmentmeans includes vertically spaced apart slots formed in said end walls ofsaid housing, tab members formed on said rail members and extendingoutwardly toward said end walls, and spring assembly means yieldinglyurging said rails against said end walls for holding said tabs withinsaid slots.

4. The lighting fixture of claim 3 wherein each said end wall includestwo pairs of said vertically spaced apart slots, the slots forming eachsaid pair being disposed adjacent opposite ends of said end walls, saidside rail members each having a pair of said tabs each adapted toregister with a slot of each said pair.

5. The device in accordance with claim 4 wherein said spring assemblymeans each includes a coupler member having a head and an elongatedshank, a vertical slot formed in each said end wall, an aperture formedin each said rail in registry with said vertical slot, said couplermember having its shank portion extending through said slot andaperture, said spring assembly means including a spring member in saidhousing having portions engaging said shank and said rail and yieldinglyurging said head portion of said coupler against the face of said endwall.

6. A lighting fixture for a hung ceiling installation comprising ahousing member including a top wall, a depending pair of spaced parallelside walls and a depending pair of spaced parallel end walls, said sideand angular in horizontal section, two opposed pairs of pivot receivermembers formed on said housing adja cent opposite ends thereof, thereceiver members of one said pair being disposed in a plane above thereceiver members of the other said pair, pivot means formed on saiddiffuser assembly and engagcable selectively with one or the other saidpairs of receiver members for pivotally coupling said diffuser assemblyto said housing, latch means on said diffuser assembly, first and secondlatch receiver means on said housing adjacent opposite ends thereof,said first and second receiver means being vertically displaced inaccordance with the vertical displacement of said pivot recciver means,whereby the vertical spacing of said diffuser assembly and said top wallportion of said housing is of a first value when said pivot means ofsaid diffuser is engaged with one said pair of pivot receiver members,and said latch means is engaged with said first receiver means, and ofdifferent value when said pivot means is engaged with the other saidpair of receiver means, and said latch means is engaged with said secondreceiver means.

7. The device of claim 6 wherein said first pair of pivot receivermembers comprises opposed slots formed in the parallel end walls of saidhousing in a first vertical plane and said second pair of pivot receivermembers comprise opposed slots in said end walls in a second verticalplane displaced from said firstplane. and said pivot means comprises apair of pins extending from said diffuser assembly, said pins beingselectively engageable with the slots of one or the other of said pairs,thereby to adjust the vertical spacing of said pins and, hence, saiddiffuser assembly from said top wall portion.

8. A lighting fixture for a hung ceiling installation comprising ahousing member including a top wall, a depending pair of spaced parallelside walls and a depending pair of spaced parallel end walls, said sideand end walls together defining a generally rectangular structure, thelower marginal edges of said walls defining a downwardly open mouthportion, a rectangular diffuser assembly including vertically extendingend and side walls defining a frame, a diffuser plate mounted withinsaid frame, said end and side walls extending above and below'the planeof said plate, a parallel pair of rail members in said housing disposedadjacent the end walls thereof, adjustment means connecting each saidrail member with an adjacent said end wall for shifting movement betweenfirst and second vertically offset positions within said housingselectively in accordance with the desired spacing of said diffuserplate from said top wall portion, pivot means on said frame adjacent afirst side thereof pivotally connecting said first side to said railmembers and latch means on the other side of said frame adapted toreleasably engage the other side of said frame with said rail members.

1. A lighting fixture for a hung ceiling installation comprising, incombination, a housing member rectangular in horizontal section andincluding a top wall, a pair of spaced parallel side walls, and a pairof spaced parallel end walls, the lower marginal edges of said wallsdefining a downwardly open, horizontal mouth portion, a light source insaid housing, a pair of parallel rail members in said housing,respectively adjacent the end walls Of said housing, adjustment meansoperatively connecting each of said rail members to said housing forsupporting said rails at a selected, predetermined, vertically adjustedposition relative to its adjacent end wall, a diffuser assemblyincluding a rectangular frame having an opening, a diffuser platemounted in said opening, hinge means adjacent one end of said framepivotally connecting said end of said frame to a corresponding pair ofsaid rail members, and releasable connector means mounted adjacent theend of said frame opposite said one end for releasably securing saidopposite end of said frame to said rail members.
 2. The lighting fixtureof claim 1 wherein said frame portion of said diffuser assembly includesa rectangular depending lip extending, in the secured position of saidframe, downwardly through said open mouth portion of said housing.
 3. Alighting fixture in accordance with claim 2 wherein said adjustmentmeans includes vertically spaced apart slots formed in said end walls ofsaid housing, tab members formed on said rail members and extendingoutwardly toward said end walls, and spring assembly means yieldinglyurging said rails against said end walls for holding said tabs withinsaid slots.
 4. The lighting fixture of claim 3 wherein each said endwall includes two pairs of said vertically spaced apart slots, the slotsforming each said pair being disposed adjacent opposite ends of said endwalls, said side rail members each having a pair of said tabs eachadapted to register with a slot of each said pair.
 5. The device inaccordance with claim 4 wherein said spring assembly means each includesa coupler member having a head and an elongated shank, a vertical slotformed in each said end wall, an aperture formed in each said rail inregistry with said vertical slot, said coupler member having its shankportion extending through said slot and aperture, said spring assemblymeans including a spring member in said housing having portions engagingsaid shank and said rail and yieldingly urging said head portion of saidcoupler against the face of said end wall.
 6. A lighting fixture for ahung ceiling installation comprising a housing member including a topwall, a depending pair of spaced parallel side walls and a dependingpair of spaced parallel end walls, said side and end walls togetherdefining a generally rectangular structure, the lower marginal edges ofsaid walls defining a downwardly open mouth portion, a light source insaid housing, a diffuser assembly adapted to be mounted within saidhousing and extend downwardly through said mouth portion, said assemblybeing rectangular in horizontal section, two opposed pairs of pivotreceiver members formed on said housing adjacent opposite ends thereof,the receiver members of one said pair being disposed in a plane abovethe receiver members of the other said pair, pivot means formed on saiddiffuser assembly and engageable selectively with one or the other saidpairs of receiver members for pivotally coupling said diffuser assemblyto said housing, latch means on said diffuser assembly, first and secondlatch receiver means on said housing adjacent opposite ends thereof,said first and second receiver means being vertically displaced inaccordance with the vertical displacement of said pivot receiver means,whereby the vertical spacing of said diffuser assembly and said top wallportion of said housing is of a first value when said pivot means ofsaid diffuser is engaged with one said pair of pivot receiver members,and said latch means is engaged with said first receiver means, and ofdifferent value when said pivot means is engaged with the other saidpair of receiver means, and said latch means is engaged with said secondreceiver means.
 7. The device of claim 6 wherein said first pair ofpivot receiver members comprises opposed slots formed in the parallelend walls of said housing in a first vertical plane and said second pairof pivot receiver members comprise opposed slots in said enD walls in asecond vertical plane displaced from said first plane and said pivotmeans comprises a pair of pins extending from said diffuser assembly,said pins being selectively engageable with the slots of one or theother of said pairs, thereby to adjust the vertical spacing of said pinsand, hence, said diffuser assembly from said top wall portion.
 8. Alighting fixture for a hung ceiling installation comprising a housingmember including a top wall, a depending pair of spaced parallel sidewalls and a depending pair of spaced parallel end walls, said side andend walls together defining a generally rectangular structure, the lowermarginal edges of said walls defining a downwardly open mouth portion, arectangular diffuser assembly including vertically extending end andside walls defining a frame, a diffuser plate mounted within said frame,said end and side walls extending above and below the plane of saidplate, a parallel pair of rail members in said housing disposed adjacentthe end walls thereof, adjustment means connecting each said rail memberwith an adjacent said end wall for shifting movement between first andsecond vertically offset positions within said housing selectively inaccordance with the desired spacing of said diffuser plate from said topwall portion, pivot means on said frame adjacent a first side thereofpivotally connecting said first side to said rail members and latchmeans on the other side of said frame adapted to releasably engage theother side of said frame with said rail members.